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If you see this weed, kill it

Garlic mustard infestation could spread from Corbett
by: File photo, More than a half-dozen agencies have combined forces to surround the noxious weed known as garlic mustard, which is about to rear its deceptively attractive head in the Corbett area.

More allies have joined the fight against an invading plant in the Columbia River Gorge and full-out war begins in mid-April.

The noxious weed known as garlic mustard is about to rear its ugly head (though the blossom is deceptively attractive) in the Corbett area. More than a half-dozen agencies have combined forces to surround the infestation, which is aiming to invade the rest of the Columbia River Gorge.

Multnomah County has the worst infestation of garlic mustard in the state, says the East Multnomah Soil and Water conservation. The plant, which exudes a chemical that kills all its neighbors, goes into bloom in the next month, making it easy to identify and easy to pull. An excellent hitchhiker, it normally travels by trails and roads and last year was growing nearly 3 feet high at the edge of the Historic Columbia River Highway east of Corbett. County and state road agencies are treating right-of-way infestations, but are powerless to deal with plants that creep onto private property. This year's campaign offers help in battling off-road infestations, but requires permission of landowners in target areas where the agencies are focusing the fight.

'The hardest part of this is getting permission from the landowners to treat the garlic mustard on their property,' said Lucas Nipp, noxious weed management technician for the East Multnomah Soil and Water Conservation District. This week his agency mailed a garlic mustard alert to homeowners in the area, explaining how to eradicate the weed and calling for cooperation

Nipp said only half of the Corbett landowners whose property is targeted for weed management responded, forcing him to send teams from his agency and The Nature Conservancy door-to-door to stake out battle lines.

In 2006 and 2007 the conservation district mapped garlic mustard along roads and trails east of the Sandy River. The mapping revealed the leading edges of the invasion - satellite plants that are carrying the infestation farther into the gorge east, south and west of Corbett.

Based on the amount of money and personnel available for this season, Nipp said his crews will use grant funds from the U.S. Forest Service and the Oregon State Weed Bureau to contain the outbreak at its perimeters.

'Working on these patches will not only ensure garlic mustard in those areas does not become out of control, but will also slow the spread of garlic mustard significantly,' Nipp says.

Contractors will spray garlic mustard in early to mid-April and then revisit sites to hand pull any that was missed. The trick is to keep on doing that for at least five years because the plant is persistent.

Corbett's Lynn Gibbons was among the first to alert Corbett-area residents to the noxious and invasive garlic mustard spreading in the Columbia River Gorge. Last year, he warned that it had reached the city limits of Troutdale.

Somehow, maybe from seeds on a hiker's boot, garlic mustard moved from the Eastern states to gain a foothold in the woodlands between Crown Point and Corbett. Gibbons was amazed at how fast the invader knocked out trilliums, ferns, even the pervasive nettle. Garlic mustard is allelopathic, meaning it excretes a chemical from its roots that is toxic to other plants.

What's left is a monoculture of garlic mustard, acres of it, poisoning and stifling trees and plants and, eventually, the creatures that live there. It seeds every five years and because it blooms biennially, it fools people by disappearing for a year and then coming back.

Agencies involved in program in addition to the conservation district, are The Nature Conservancy, Oregon Parks and Recreation Department, Multnomah County and the Oregon Department of Transportation.